Biology

Nervous System and Neurons

1,164 Questions

The nervous system and neurons section covers the structural and functional aspects of the human nervous system. Topics include nerve fibers, the myelin sheath, and sympathetic nervous system functions. This material is crucial for general science preparation in various competitive exams.

Neuron structureMyelin sheath productionSympathetic nervous systemCranial and spinal nervesParasympathetic functions

Nervous System and Neurons Questions

Multiple choice biology structural organization of animals structural organization of rabbit structural organization of leech phylum annelida

Two extra cranial nerves found in rabbit/human are

  1. Hypoglossal and spinalaccessory

  2. Hypoglossal and pneumogastric

  3. Spinal accessory and glossopharyngeal

  4. Hypoglossal and glossopharyngeal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

While many vertebrates have 10 pairs of cranial nerves, mammals (including rabbits and humans) possess 12 pairs. The two additional pairs are the hypoglossal (XII) and the spinal accessory (XI).

Multiple choice zoology neural control and coordination parts of the brain brain and its parts brain

Anaesthetics reduce pain by blocking nerve conduction due to

  1. Blocking neurotransmitter receptors
  2. Blocking N$a^+$ channels
  3. Blocking $K^+$ channels

  4. All the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Local anaesthetics work primarily by binding to and blocking voltage-gated sodium channels in nerve cell membranes, which prevents the depolarization required for nerve impulse conduction.

Multiple choice how humans hear sound human ear study of sound sound physics

What stimulates the auditory nerve?

  1. the movement of the three ear ossicles

  2. the movement of stirrup

  3. the movement of fluid in the cochlea

  4. all
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cochlea is a coiled and fluid filled tube having sense of hearing. The movement of the fluid in the cochlea due to the vibrations stimulates the auditory nerve .

Multiple choice how humans hear sound human ear study of sound sound physics

What stimulates the auditory nerve?

  1. The movement of the three ear ossicles

  2. The movement of stirrup

  3. The movement of fluid in the cochlea

  4. All of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cochlea is a coiled and fluid filled tube having sense of hearing.the movement of the fluid in the cochlea due to the vibrations stimulates the auditory nerve.

Multiple choice biology biodiversity and its classifications life introduction to plant kingdom classification of organisms

Nerve cord is in ............ position in invertebrates.

  1. Dorsal

  2. Lateral

  3. Ventral

  4. Absent
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The ventral nerve cord is a bundle of nerve fibers, typically a solid double strand (pair) of nerve cords, that runs along the longitudinal axis of some phyla of elongate invertebrates, and forms part of the invertebrate central nervous system. In most cases, this nerve cords runs ventrally, below the gut, and connects to the cerebral ganglia. Among the phyla exhibiting ventral nerve cords are nematodes (roundworms), annelids (such as earthworms, and arthropods (such as insects and crayfish).
The ventral nerve cord usually consists of a pair of partially fused nerve trunks running longitudinally along the ventral plane of the animals, from the anterior to posterior (the thoracic and abdominal tagma in the arthropods).

So, the correct answer is option A.

Multiple choice biology the age of adolescence changes in body during adolescence hormone during puberty role of hormones in reproduction

The homeostatic regulation of an animal requires three basic components, ________ to detect changes, ________ to evaluate the changes and _______ to adjust the changes respectively.

  1. Receptors, control center, effectors

  2. Brain, spinal cord, effectors

  3. Receptors, integrators, effectors

  4. Receptors, effectors, integrators
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Homeostatic regulation involves receptors (detecting stimuli), a control center (evaluating information), and effectors (executing the response to restore balance).

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Reflex arc is formed by 

  1. Receptor - brain - muscles

  2. Muscles - spinal cord - receptor

  3. Receptor - spinal cord - muscles

  4. Muscle - brain - receptor
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The reflex arc is a simple nervous pathway and consists of the sensory receptor, afferent neuron, centre, efferent neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to the spinal cord (sensory pathway). Reflex arc starts with sensory receptors, not with muscles. The interneurons of spinal cord integrate the incoming information and signal is relayed to motor/efferent neurons.  The motor pathway transmits the signal from motor neurons to the effector organs (muscles and glands etc). Thus, reflex arc transmits the information from receptor to effector via the spinal cord which. The brain is not the part of reflex arc. Thus, the correct answer is option C.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

The sequence of a reflex arc is

  1. Receptor $\rightarrow$ Sensory neuron $\rightarrow$ Motor neuron $\rightarrow$ Effector $\rightarrow$ Response
  2. Effector $\rightarrow$ Sensory neuron $\rightarrow$ Motor neuron $\rightarrow$ Receptor $\rightarrow$ Response
  3. Effector $\rightarrow$ Motor Neuron $\rightarrow$ Interneuron $\rightarrow$ Receptor $\rightarrow$ Response
  4. Receptor $\rightarrow$ Motor neuron $\rightarrow$ Sensory neuron $\rightarrow$ Effector $\rightarrow$ Response
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Reflex arc transmits the sensory information from receptor to effector via spinal cord. It consists of sensory receptor, afferent (sensory) neuron, centre, efferent (motor) neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to spinal cord (sensory pathway). Detection of environmental stimulus by receptors forms the first step of reflex arc. 

Sensory neurons receive the information from receptors while motor neurons transmit the nerve impulses from CNS to effectors (muscles and glands). 
The interneurons of spinal cord integrate the incoming information and signal is relayed to motor/efferent neurons.  The motor pathway transmits the signal from motor neurons to the effector organs (muscles and glands etc). The effector organs respond according to the information carried by motor pathway.
Therefore, the correct answer is option A.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

The reflex arcs in which one or more interneurons connect the afferent and efferent signals are

  1. Autonomic reflex

  2. Somatic reflex

  3. Monosynaptic reflex

  4. Polysynaptic reflex
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  • Monosynaptic reflex is a type of reflex in which the reflex arc consists of only two neurons, one sensory neuron, and one motor neuron. Monosynaptic refers to the presence of a single chemical synapse. 
  • By contrast, in polysynaptic reflex arcs, more than one relay neurons connect the sensory and motor neuron. 
  • Polysynaptic reflex or spinal reflex or withdrawal reflex protects the body from the damaging stimulus. It is located in the spinal cord. 

Therefore, the correct answer is option D.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Simple two neuron reflex arc involves

  1. Sensory neuron

  2. Spinal cord

  3. Effector neuron

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Reflex arc transmits the sensory information from receptor to effector via the spinal cord. It consists of the sensory receptor, afferent neuron, centre, efferent neuron and effector organ. The afferent/sensory neurons transmit the sensory information from sensory receptors to the spinal cord (sensory pathway). The interneurons of spinal cord integrate the incoming information and signal is relayed to motor/efferent neurons. The motor pathway transmits the signal from motor neurons to the effector organs (muscles and glands etc). 

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Route of reflex arc is

  1. Effectors, grey matter, motor fibres, sensory fibres and receptors

  2. Receptors, sensory fibres, grey matter and motor fibres

  3. Receptors, sensory fibres, grey matter, motor fibres and effectors

  4. Sensory fibres, grey matter, motor fibres, receptors and effectors
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A reflex arc follows a specific pathway: a receptor detects a stimulus, sensory neurons transmit the signal to the central nervous system (grey matter), motor neurons carry the response, and effectors perform the action. Option C correctly lists this sequence.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc
During reflex the sensory neurons do not pass directly to the brain.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The path taken by the nerve impulses in a reflex is called as a reflex arc. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This characteristic allows reflex actions to occur relatively quickly by activating spinal motor neurons without the delay of routing signals through the brain, although the brain will receive sensory input while the reflex action occurs. 

Therefore, the correct answer is option A.

Multiple choice biology nervous system the reflex action reflex action and reflex arc basic reflex action and reflex arc

Put the following parts of a reflex arc in the correct order beginning with the sensory receptor.
A. Motor neuron    B. Interneuron    C. Effector    D. Sensory neuron     E. Sensory receptor

  1. E, D, B, A, C

  2. E, D, A, B, C

  3. A, B, C, D, E

  4. A, E, D, B, C
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Most reflex arcs have five main components:  receptors, sensory neurons,interneurons, motor neurone and muscles.
Neurons have special proteins called receptors. Receptors respond to signals in the environment like pressure, pain, vibrations, light etc.
Sensory neurons have sensory receptors, they get activated by the signal from the environment. The activated sensory neurons extend into spinal cord sending an electrical signal to another neuron, the interneuron.
Interneuron then relays the signal to the motor neuron. Motor neuron run out of spinal cord and connect with the muscle or effector.
Thus the correct sequence is a sensory receptor, sensory neuron, interneuron, motor neuron and last effector.